message_view.php: fix PHP references warning
message_view.php: fix PHP references warning

Fix "Only variables should be assigned by reference" warnings.

Also remove a bunch of unnecessary uses of references. See #317.

hemberger/smr,hemberger/smr,smrealms/smr,hemberger/smr,hemberger/smr,smrealms/smr,smrealms/smr